docstr: Salzer summation weights (aka, "Stehfest coefficients")
  only depend on the approximation order (M) and the precision
docstr_tok: ["Salzer","summation","weights","(","aka",",","``","Stehfest","coefficients","''",")","only","depend","on","the","approximation","order","(","M",")","and","the","precision"]
code: def _coeff(self):
      r"""Salzer summation weights (aka, "Stehfest coefficients")
      only depend on the approximation order (M) and the precision"""
  
      M = self.degree
      M2 = int(M / 2)  # checked earlier that M is even
  
      V = self.ctx.matrix(M, 1)
  
      # Salzer summation weights
      # get very large in magnitude and oscillate in sign,
      # if the precision is not high enough, there will be
      # catastrophic cancellation
      for k in range(1, M + 1):
          z = self.ctx.matrix(min(k, M2) + 1, 1)
          for j in range(int((k + 1) / 2), min(k, M2) + 1):
              z[j] = (
                  self.ctx.power(j, M2)
                  * self.ctx.fac(2 * j)
                  / (
                      self.ctx.fac(M2 - j)
                      * self.ctx.fac(j)
                      * self.ctx.fac(j - 1)
                      * self.ctx.fac(k - j)
                      * self.ctx.fac(2 * j - k)
                  )
              )
          V[k - 1] = self.ctx.power(-1, k + M2) * self.ctx.fsum(z)
  
      return V
  
label_desc: Use image node_id 2 for calling the Stehfest obj's underlying member method code with example usage: obj._coeff() and returns: V